Selective Harmonic Elimination in Multi-Modules Three-Phase Current-Source Converters

Modular current source converters (MCSC) can enhance the current capacity and improve the power quality at medium voltage PWM motor drives. A MCSC uses individual three-phase modules in a shunt connection to share the total power in a symmetrical manner. The modulation of these units is normally done using optimized patterns as selective harmonic elimination (SHE). However, the optimization is usually performed at each module. This paper proposes a modulating technique that optimizes the operation of a MCSC built up of P modules. Thus, for the same switching frequency, P times the number of harmonics are removed from the injected ac current as compared to the regular approach. A complete mathematical formulation as well as experimental results validate the theoretical considerations